Method and apparatus for wireless communication with dual connectivity

Abstract

A method and an apparatus for wireless communication with dual connectivity are described. The apparatus supports dual connectivity with a first cell and a second cell and the apparatus comprises a radio frequency (RF) and a processor operatively coupled to the RF unit. The second cell is an overlaid virtual cell which is formed by collaborating the first cell and cell ID of the second cell is different from physical cell ID of the first cell when the processor uses primary synchronization signal (PSS), secondary synchronization signal (SSS) or cell-specific common reference signal (CRS) as synchronization signal for the second cell.

The invention claimed is: 
     
       1. A user equipment (UE) for supporting dual connectivity with a small cell and a virtual cell, the UE comprising:
 a radio frequency (RF) unit configured to transmit and receive a radio signal; and 
 a processor, operatively coupled to the RF unit, that:
 attaches the virtual cell as a serving cell in the dual connectivity, wherein the virtual cell overlapped with the small cell is formed by combining the small cell and a plurality of neighboring cells of the small cell; 
 attaches the small cell as a secondary cell in the dual connectivity, wherein the small cell is a cell in which the UE is located; 
 controls the RF unit to receive control plane data at a multimedia broadcast single frequency network (MBSFN) subframe, from the virtual cell; and 
 controls the RF unit to receive user plane data, from the small cell, 
 wherein a cell identity (ID) of the virtual cell is different from a physical cell ID of the small cell when a primary synchronization signal (PSS), a secondary synchronization signal (SSS) or a cell-specific common reference signal (CRS) is used as a synchronization signal for the virtual cell, and 
 wherein the virtual cell supports maintaining a control plane of the UE. 
 
 
     
     
       2. The UE of  claim 1 , wherein the processor:
 controls the RF unit to transmit the control plane data, to the virtual cell; and 
 controls the RF unit to transmit the user plane data, to the small cell. 
 
     
     
       3. The UE of  claim 1 , wherein the processor:
 derives a cell ID of the small cell using synchronization signal; and 
 uses an MBSFN reference signal as a reference signal for demodulating the control plane data received from a control channel of the virtual cell. 
 
     
     
       4. The UE of  claim 1 , wherein the processor:
 derives a cell ID of the small cell using a synchronization signal; and 
 uses a demodulation reference signal as a reference signal for demodulating the control plane data received from a control channel of the virtual cell. 
 
     
     
       5. The UE of  claim 1 , wherein the processor:
 performs rate-matching for a CRS resource element when a CRS is used for demodulating the control plane data received from a control channel of the virtual cell. 
 
     
     
       6. The UE of  claim 1 , wherein the UE supports the dual connectivity with a first cell having a cell ID that is different from the physical cell ID of the small cell, and
 wherein the control plane data of the virtual cell and data of the first cell are transmitted at a same MBSFN subframe. 
 
     
     
       7. A method for supporting connectivity with a small cell and a virtual cell, by a user equipment (UE), the method comprising:
 attaching the virtual cell as a serving cell in the dual connectivity, wherein the virtual cell overlapped with the small cell is formed by combining the small cell and a plurality of neighboring cells of the small cell; 
 attaching the small cell as a secondary cell in the dual connectivity, wherein the small cell is a cell in which the UE is located; 
 receiving control plane data at a multimedia broadcast single frequency network (MBSFN) subframe, from the virtual cell; and 
 receiving user plane data, from the small cell, 
 wherein a cell identity (ID) of the virtual cell is different from a physical cell ID of the small cell when a primary synchronization signal (PSS), a secondary synchronization signal (SSS) or a cell-specific common reference signal (CRS) is used as a synchronization signal for the virtual cell, and 
 wherein the virtual cell supports maintaining a control plane of the UE. 
 
     
     
       8. The method of  claim 7 , further comprising:
 transmitting the control plane data, to the virtual cell; and 
 transmitting the user plane data, to the small cell. 
 
     
     
       9. The method of  claim 7 , wherein a cell ID of the small cell is derived using a synchronization signal, and
 wherein an MBSFN reference signal is used as a reference signal for demodulating the control plane data received from a control channel of the virtual cell. 
 
     
     
       10. The method of  claim 7 , wherein a cell ID of the small cell is derived using a synchronization signal, and
 wherein a demodulation reference signal is used as a reference signal for demodulating the control plane data received from a control channel of the virtual cell. 
 
     
     
       11. The method of  claim 7 , wherein rate-matching for a CRS resource element is performed when a CRS is used for demodulating the control plane data received from a control channel of the virtual cell. 
     
     
       12. The method of  claim 7 , wherein dual connectivity is supported with a first cell having a cell ID that is different from the physical cell ID of the small cell, and
 wherein the control plane data of the virtual cell and data of the first cell are transmitted at a same MBSFN subframe.